1. Field of the Invention
The invention relates to discarding sabot projectiles, and more specifically to sub-caliber fin-stabilized armor penetrating projectiles, which contain therein rod penetrator cores, and an integral tracer of suitable pyrotechnic composition.
2. Description of the Prior Art
Three types of armor piercing projectiles are currently utilized in small caliber gun systems. One of the designs is of a conventional projectile shape and is full-bore diameter, consisting of a combination of high strength steel or high density material as a penetrator swaged or inserted into a suitable jacket or sleeve material. At the projectile base is an opening for a tracer cavity of adequate depth and diameter to provide a clear visual trace of the entire projectile trajectory. This type of full-bore projectile utilizes the high density or high strength penetrator and to some extent the jacket or sleeve material and its geometry to affect armor penetration. This type of projectile has severely limited armor penetration capability at target engagement ranges beyond several hundred meters, due to its high drag configuration.
It has been demonstrated that sub-caliber high density rod type penetrators are capable of penetrating significantly more armor than the full-bore projectiles at target ranges beyond several hundred meters. This is due to the high density rod's more efficient armor penetration geometry and the greater mass per cross sectional area of the sub-caliber rod flight projectile, which results in it losing less velocity from aerodynamic drag. To take advantage of the rod's high ballistic coefficient and to provide increased initial launch velocities, sabots were designed to encapsulate the rod penetrator during handling, storage, and gun firing, and to discard shortly after exiting the muzzle, thus allowing only the rod penetrator to continue in flight toward the target. One type of discarding sabot projectile has been demonstrated in small caliber guns to provide increased armor penetration over full-bore projectiles. This is the Armor Piercing Discarding Sabot (APDS) projectile, which utilizes a spin stabilized sub-caliber penetrating core as the flight projectile. APDS projectiles using high density rod penetrators have been developed for guns from caliber 5.56 millimeter through caliber 120 millimeter. Given aerodynamic considerations, APDS projectile designs below caliber 25 millimeter do not allow the inclusion of a tracer cavity without degrading penetrator performance. The tracer cavity in these projectiles significantly reduces the available high density rod material required for armor penetration.
It has been demonstrated that armor piercing fin stabilized discarding sabot (APFSDS) projectiles penetrate more armor at greater ranges than spin stabilized APDS projectiles, due to the longer allowable penetrator lengths that can be launched and flown to the target with accuracy and stability. APFSDS projectiles utilizing high density sub-caliber rod penetrators have been developed for both rifled barrel and smooth bore guns from caliber 25 millimeter through 140 millimeter, and these designs have permitted the incorporation of an adequate tracer cavity in the rear of the flight projectile without degradation of the rod's armor penetration performance. Flechette type APFSDS projectiles utilizing high strength or high density rod penetrators have been developed for small caliber 5.56 and 7.62 millimeter rifle systems, but without allowance for a tracer cavity in the flight projectile.
Fin stabilized APFSDS projectile designs incorporating an adequate tracer cavity and developed for larger caliber systems do not efficiently scale down to small caliber projectiles due to the complexity of their sabot geometries which were optimized for the unique parameters of the larger caliber systems. Early fin stabilized APFSDS projectile designs for smaller caliber 5.56 and 7.62 millimeter guns did not provide for a tracer cavity in the rear of the flight projectile.
A more effective and efficient fin-stabilized, discarding sabot projectile incorporating an adequate tracer cavity with a deep armor penetrating projectile for small arms applications has been disclosed in U.S. Pat. No. 5,297,492 (Buc). This design overcomes many of the shortcomings inherent in earlier small arms APDS and APFSDS projectiles, such as: faulty structural design, poor sabot discard, reduced projectile accuracy at long range, low muzzle velocity due to high sabot parasitic weight, and inadequate armor penetration. Although a good start in the right direction for small caliber APFSDS projectiles, this design requires the use of several high precision manufactured obturator components, to ensure adequate performance and safety reliability. Reducing the complexity of the current state-of-the-art in obturator design will result in greater projectile performance, achieved with less expensive components, assemblies, and manufacturing processes.
Accordingly, it is advantageous to provide an armor piercing fin stabilized discarding sabot (APFSDS) projectile for small caliber guns which minimizes sabot parasitic weight and structural complexity, facilitates rapid sabot separation upon muzzle exit without introducing trajectory inaccuracies for the rod projectile, maximizes armor penetrator weight and length, and provides for an adequate tracer cavity in the rear of the flight projectile.